The Effect of Shear on the Evolution of Morphology in High Internal Phase Emulsions Used as Templates for Structural and Functional Polymer Foams,ACS Applied Polymer Materials

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The Effect of Shear on the Evolution of Morphology in High Internal Phase Emulsions Used as Templates for Structural and Functional Polymer Foams
ACS Applied Polymer Materials ( IF 4.4 ) Pub Date : 2020-02-25 , DOI: 10.1021/acsapm.0c00003
Reza Foudazi _{1,

2} , Boran Zhao ₃ , Polina Gokun ₂ , Ica Manas-Zloczower ₂ , Stuart J. Rowan _{2,

4} , Donald L. Feke ₃

Affiliation

Polymer foams have broad application as structural and functional materials in a variety of technological applications. Polymerization of monomers present in the continuous phase of water-in-oil high internal phase emulsions (HIPEs) provides a unique processing route for fabricating highly porous polymeric foams known as polyHIPEs. The microstructure of the polyHIPEs is related to the morphology of the HIPE from which it is templated. Shear-induced microstructural changes within the HIPE result from the combination of droplet breakup and coalescence induced by shear or thermal diffusion. HIPEs were prepared from a two-component oil phase consisting of 2-ethylhexyl acrylate (2-EHA) and ethylene glycol dimethacrylate monomers. Imaging of the HIPEs revealed shifts in the mean and polydispersity of the droplet size distribution with repeated shearing. Isothermal, oscillatory time-sweep chemorheological studies, conducted in the linear viscoelastic regime, were used to gain insights about the kinetics of polymerization as well as the morphological changes due to the thermal-induced droplet coalescence. The compressive modulus of wet polyHIPEs was found to increase with decreasing cell size and to decrease when coalescence occurred within the precursor HIPE. Thermal gravimetric analysis revealed an enhancement in the 2-EHA composition within the polymer compared to the original oil phase, presumably due to a difference in solubilities of the two monomer components into the aqueous phase.

中文翻译：

剪切对高内相乳液（用作结构和功能聚合物泡沫的模板）中形态演变的影响

聚合物泡沫在各种技术应用中作为结构和功能材料具有广泛的应用。存在于油包水型高内相乳液（HIPEs）的连续相中的单体的聚合为制造被称为polyHIPEs的高度多孔的聚合物泡沫提供了独特的工艺路线。polyHIPEs的微观结构与HIPE的模板结构有关。HIPE内的剪切诱导的微观结构变化是由于剪切或热扩散引起的液滴破裂和聚结的结果。HIPE由丙烯酸2-乙基己酯（2-EHA）和乙二醇二甲基丙烯酸酯单体组成的两组分油相制备。HIPEs的成像显示，在反复剪切下，液滴尺寸分布的平均值和多分散性发生了变化。在线性粘弹性条件下进行的等温，振荡时间扫描化学流变学研究用于获得有关聚合动力学以及由于热诱导液滴聚结而引起的形态变化的见解。发现湿聚HIPE的压缩模量随着孔尺寸的减小而增加，并且在前体HIPE内发生聚结时降低。热重量分析表明，与原始油相相比，聚合物中的2-EHA组成有所增强，这可能是由于两种单体组分在水相中的溶解度不同所致。用来获得关于聚合动力学以及由于热诱导液滴聚结而引起的形态变化的见解。发现湿聚HIPE的压缩模量随着孔尺寸的减小而增加，并且在前体HIPE内发生聚结时降低。热重量分析表明，与原始油相相比，聚合物中的2-EHA组成有所增加，这可能是由于两种单体组分在水相中的溶解度不同所致。用来深入了解聚合动力学以及由于热诱导液滴聚结而引起的形态变化。发现湿聚HIPE的压缩模量随着孔尺寸的减小而增加，并且在前体HIPE内发生聚结时降低。热重量分析表明，与原始油相相比，聚合物中的2-EHA组成有所增加，这可能是由于两种单体组分在水相中的溶解度不同所致。

更新日期：2020-02-25

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